Acetone extraction of mcl-PHA from Pseudomonas putida KT2440

A methodology was developed for the extraction of medium-chain-length poly-3-hydroxyalkanoates (mcl-PHA) from Pseudomonas putida. It was determined that if dry P. putida biomass containing mcl-PHA was washed in 20 volumes of methanol for 5 min followed by Soxhlet extraction in 10 volumes of acetone for 5 h, almost all of the PHA could be recovered with no detectable loss of molecular weight. Biomass containing higher amounts of PHA required less methanol during the pretreatment step but more acetone in the solvent extraction step than biomass containing less PHA. Further purification could be achieved by redissolving the PHA in acetone and reprecipitating in cold methanol. UV spectroscopy at 241 and 275 nm could be used as an indication of product purity.